Apparatus for fragmenting automobile tires

ABSTRACT

Automobile tires and analogous articles of rubber or synthetic plastic material are frozen to make them brittle, and thereupon are fragmented in order to separate their rubber or synthetic plastic material from embedded reinforcements of textile or analogous fabrics. The fragmenting is carried out by dropping the articles into an impact mill in which a rotor equipped with striking elements turns about a horizontal axis, so that the articles are hit by the striking elements of the rotor and flung in circumferential direction of movement of the rotor against impact plates from which they drop back onto the rotor, whereby the articles are fragmented by the repeated hits and impacting. An apparatus for carrying out the method is also disclosed.

BACKGROUND OF THE INVENTION

The present invention relates generally to the fragmenting of articlesmade from rubber or synthetic plastic material, and more particularly tothe fragmenting of such articles, and in particular of automobile tires,which contain reinforced embedments of textile or other substances, suchas wire mesh or the like.

It has long been the general practice to discard automobile tires andanalogous articles made of rubber or synthetic plastic material whichhave become worn and unuseable. The general practice has been to eitherbury such articles or to burn them. In recent years, however, it hasbeen recognized that it is unwise economically and ecologically todiscard so large a source of potentially recoverable materials,especially in an age of dwindling supplies of raw materials. It hastherefore been proposed in the prior art to provide equipment forrecovering the rubber or synthetic plastic material of automobile tiresor analogous articles which have become otherwise unuseable.Particularly in the case of automobile tires, this essentially presentsthe problem of separating the rubber or synthetic plastic of the tirefrom the textile or metallic reinforcements which are embedded in thetire.

The prior art has proposed to freeze the articles to be processed, basedon on the well known fact that rubber and synthetic plastic materialbecome brittle when frozen and can therefore be more readily fragmented.Thus, one prior-art proposal suggests to freeze the tires, place themflat upon an anvil plate and pound them with a mechanically orhydraulically actuated hammer or ram which is intended to fragment thetire.

Unfortunately, the prior-art approach has not been entirelysatisfactory, because a satisfactory separation of the rubber orsynthetic plastic material from the embedded reinforcements could not beobtained. Even if the blows upon the tire, which term hereafter will beused generically to refer to all articles whose rubber or syntheticplastic material is to be recovered, are repeated several times, theresults are not satisfactory because the hammer hits the tire always inthe same places. Especially the rather strong and resistant wire ringswhich are embedded in the bead of the tire are hit always transverse totheir general plane, so that they are not subjected to any bendingstresses and do not become satisfactorily separated from the tirematerial. When subsequently the more or less fragmented tire is passedthough a magnetic separator to remove any wire or metallic componentsfrom it, these metallic components always take along a rather largeproportion of the rubber or synthetic plastic material which stilladheres to them and has not been satisfactorily separated from them, andthis proportion is either lost or must be removed by a separate andexpensive operation. If textile reinforcements are involved which alsocannot be satisfactorily removed according to the prior art, then theycontinue with the more or less fragmented tire material into asubsequent comminuting mill in which they are comminuted together withthe rubber or synthetic plastic tire material and contaminate thismaterial.

SUMMARY OF THE INVENTION

Accordingly, it is a general object of the invention to overcome thedisadvantages of the prior art as outlined above.

More particularly, it is an object of the present invention to providean improved apparatus for fragmenting articles of rubber or syntheticplastic material, and separating such material from any embeddedreinforcements of a textile or other character.

In keeping with the above objects, and with others which will becomeapparent hereafter, one feature of the invention resides in an apparatusfor fragmenting automobile tires and analogous articles of rubber orsynthetic plastic material which have been frozen to make them brittle,so as to separate their material from embedded reinforcements of textileor analogous substances, and in this apparatus a combination is providedwhich comprises a impact mill or impactor with a rotor mounted forrotation about a horizontal axis and having a plurality ofcircumferentially spaced striking elements which move about said axis inan orbital path having an apex to which said striking elements moveupwardly from below at one side of the axis and from which they movedownwardly at the other side of the axis. Feeding means is provided forgravity-feeding articles to be fragmented in a downward direction to behit by the striking elements at the one side and in the region of theapex. A housing surrounds the rotor and forms a chamber extending fromthe feeding means in direction of rotation of the rotor, and impactelements are arranged in this chamber above the rotor and at its otherside and so spaced from the rotor that articles hit by the strikingelements are freely flung against the impact elements and can drop backupon the rotor to be hit again.

The invention is based upon the quite surprising and unexpected findingthat a proper fragmentation of tires or other articles of syntheticplastic or rubber material can be obtained, with a concomitant completerelease of such material from embedded reinforcements, if thefragmentation is carried out in an impactor having the type mentionedabove. Impactors of this general type are, for instance, known from U.S.Pat. No. 3,602,444. It has been found that the purposes of the inventionand the advantages achieved thereby can be obtained only by using thistype of impactor, that is an impactor having the aforementioned rotorwhich rotates about a horizontal axis and which has striking elementsthat strike the incoming material and fling it in the direction ofrotation of the rotor against impact plates from which the material thenfalls back upon the rotor. Other types of mechanical fragmentingapparatus, such as for instance hammermills, are not suitable and cannotobtain the advantages and purposes of the present invention.

It is important in accordance with the invention that the tires andother articles which are hit by the orbiting striking members of therotor be freely flung against the impact plates, because only in thismanner is it possible to attain an almost complete separation of thetire material from wire or textile reinforcements embedded in it withoutat the same time experiencing a fragmenting of the reinforcements intosmall pieces which might cling to the tire material per se and bedifficult or impossible to separate from it during the later processing.The reason for this advantage is that in an impactor of the type inquestion the tires or other articles are in effect subjected only torandom impacts so that the impact forces act upon the article atdifferent times in many different directions, rather than acting more orless consistently in one general direction for the entire time or formost of the time as in the prior art.

It was found that quite surprisingly the fragmented articles will leavean impactor, after having been processed according to the presentinvention, in a condition in which the reinforcements are almostentirely free of adhering rubber or synthetic plastic material, and inwhich the reinforcements have assumed a tangled ball-shaped orknot-shaped configuration and can thus be readily separated from therubber or synthetic plastic fragments by screening. Moreover, thefragmenting of a tire or analogous article proceeds very rapidly whencarried out according to the present invention, so that the rubber orplastic fragments, which leave the impactor free of any embeddedreinforcements, are still sufficiently cold from the previous freezingso that they can be further broken up into smaller particles by thenpassing them through a hammermill.

The time required to fragment an individual tire or analogous article inaccordance with the present invention is only on the order ofapproximately 6-10 seconds. This means that it is possible to admit thetires or similar articles individually and one-at-a-time into theimpactor, so that the fragmenting of a preceding article is completed oralmost completed by the time the next article is admitted into theimpactor, whereby improved impacting and fragmenting is obtained. Due tothe very brief time required for the fragmenting of each individualarticle, even the separate and successive admission of the articles intothe impactor makes it possible to obtain a throughout of approximately300-600 tires or similar articles per hour, which is an excellent andeconomically highly advantageous figure. It is particularly helpful ifthe housing and rotor width--in the direction of the axis of rotation ofthe rotor--are relatively narrow so that the tires or similar articlescannot be admitted and impacted while in a lying down condition, butmust more or less stand on edge. It has been found that this isadvantageous because the fragmentation and separation of the tirematerial from the reinforcements is particularly good when, at least atthe beginning of the operation, the hits act upon the tire more or lessradially from the outer periphery thereof, to assure that thereinforcements, including the wire reinforcing rings in the beads of thetire, are subjected to high bending stresses. It is also advantageous ifneither the striking elements on the rotor itself, nor the impact platesagainst which the tires are flung by the rotor, have any projections,teeth or the like, but are all smoothed-surfaced, including their edges.This prevents entangeling of the separated reinforcements on theseelements since there is nothing in the way of projections or the likeonto which these reinforcements could hook themselves.

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following description of specificembodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING

The single FIGURE is a diagrammatic side view, partly in section,illustrating an apparatus or carrying out the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The apparatus according to the present invention has been illustratedonly relatively diagrammatically, because it is believed that this issufficient for an understanding of the invention. The type of rotor usedin the apparatus, and the general operation of an impactor of the typewhich will be discussed with respect to the FIGURE, is already known,for instance from the aforementioned U.S. patents. An installation forfreezing tires or other articles made from rubber or synthetic plasticmaterial, for the purpose of making them brittle and more readilyfragmentizable, is also disclosed from the art, for instance from Germanpatent application 2,155,380, and directs streams of a liquefied gasover the tires. Of course, the tires could also be dipped into a body ofliquefied gas, or otherwise be refrigerated to the necessary extent.

Referring now specifically to the FIGURE, it will be seen that referencenumeral 1 identifies an impactor having an inlet hood 2. A belt or otherconveyor 3 identifies a feeding arrangement by means of which frozenarticles 8, here illustrated as old tires, are conveyed into the hood 2.

The housing of the apparatus surrounds a chamber 9 in which the rotor 11is mounted for rotation in counterclockwise direction. When the tires 8are discharged from the conveyor 3 and allowed to drop under theinfluence of gravity into the chamber 9 by rolling or sliding downwardlyinto it, they enter the region of the orbital path of the elongated (inthe direction of the axis of rotation of the rotor) striking elements orbars 10 which are mounted on the rotor circumferentially distributedthere about. Since the rotor turns in counterclockwise direction, thestriking elements 10 move in upward direction on the right-hand side ofthe axis of rotation, until they reach the apex of their movement, andthen begin to move downwardly from the apex on the left-hand side of theaxis of rotation. The term right-hand and left-hand side refers to theillustration, where the axis of rotation is horizontal or substantiallyso. The tires 8 therefore are hit in the region of the right-hand sideof the axis of rotation, and the striking takes place with very greatforce since the rotor can rotate at high speed. Because the tires arebrittle due to the previous refrigeration, they are already broken apartwith the first hit received from one of the striking elements 10 whichat the same time flings the tire in the direction of rotation towardsthe left against the first impact plate 12 which is spaced far enoughfrom the rotor so that the tires can be freely flung against them. Whena tire hits this impact plate 12, it becomes again further fragmented.Because of the manner in which the impact plates 12 are mounted withrespect to the rotor, the fragments can fall off the impact plates andback onto the rotor where they receive further hits by the strikingelements 10.

In a surprisingly brief period of time, that is approximately 6-10seconds for a tire, the material of the tire is fragmented to such anextent that it has completely or almost completely become separated fromthe embedded reinforcements and can now drop out of the chamber 9through the illustrated lower outlet thereof. The impact plates 12 maybe made adjustable, as diagrammatically shown, in order to be able toset them to different optimum positions that might be required independence upon different materials being fragmented.

Arranged below the outlet of the chamber, so as to receive thefragmented rubber or synthetic plastic particles and the reinforcementmaterial which has been separated from them, is a screen arrangement 4,that is for instance an arrangement provided with a vibratory screenonto which the material drops. The vibration of the screen causes therubber or synthetic plastic fragments to fall through the openings ofthe screen, whereas the reinforcement material is retained on the screenand can be discarded. The reference numeral 14 identifies a conveyoronto which the reinforcement material and any rubber or syntheticplastic fragments which are too large to pass through the openings ofthe screen, can slide--seeing as the screen 4 is inclined downwardly tothe conveyor 14--and which carries them away.

The material that has passed through the screen 4 may drop onto ametering device 5 whose particular construction is of no consequence forthe invention, and which can discharge metered quantities of thismaterial into a hammermill 6 of conventional construction, wherein thefragments are made still smaller by being pounded with hammers, to besubsequently discharged and carried on a conveyor 7 to the receptacle 13for further use.

The present invention thus provides for an apparatus for fragmentingtires and analogous articles and separating their rubber or syntheticplastic material from embedded reinforcements, which avoid thedisadvantages of the prior art and permit a rapid and highly economicalrecovery of the rubber or synthetic plastic material for further use.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofconstructions differing from the type described above.

While the invention has been illustrated and described as embodied inthe fragmenting of articles of rubber or synthetic plastic material andthe separation of embedded reinforcements from such material, it is notintended to be limited to the details shown since various modificationsand structural changes may be made without departing in any way from thespirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can by applying current knowledge,readily adapt it for various applications without omitting features thatfrom the standpoint of prior art fairly constitute essentialcharacteristics of the generic or specific aspects of this invention.

I claim:
 1. In an apparatus for fragmenting automobile tires andanalogous articles of elastomeric material such as rubber or syntheticplastic material which have been frozen to make them brittle, so as toseparate their material from embedded reinforcements of textile or othersubstances, a combination comprising an impact mill with a rotor mountedfor rotation about a horizontal axis and having a plurality ofcircumferentially spaced smooth-surfaced striking elements which moveabout said axis in an orbital path having an apex to which said strikingelements move upwardly from below at one side of said axis, and fromwhich they move downwardly at the other side of said axis; feeding meansfor gravity feeding articles to be fragmented in a downward direction,to be hit by said striking elements at said one side and in the regionof said apex; a housing surrounding said rotor and forming a chamberextending from said feeding means in direction of rotation of saidrotor, said chamber having an outlet for fragments of elastomericmaterial and for the reinforcements; smooth-surfaced impact elementsarranged in said chamber above said rotor and at said other side and sospaced from said rotor that articles hit by said striking elements arefreely flung against the impact elements and can freely drop back uponsaid rotor to be hit again, whereby said elastomeric material isfragmented and the reinforcements become detached from the elastomericmaterial; and means for segregating said fragments of elastomericmaterial from the detached reinforcements.
 2. A combination as definedin claim 1, wherein said chamber has a width in direction of said axiswhich is smaller than the diameter of said articles.
 3. A combination asdefined in claim 1, wherein said articles are tires; and wherein saidchamber has a width in direction of said axis which is equal tosubstantially half the diameter of said tires.
 4. A combination asdefined in claim 1, wherein said feeding means comprises feedingconveyor means for feeding each article into said chamber individuallyand only when the preceding article is already at least substantiallyfragmented, so that no more than one article is being fragmented at atime.
 5. In an apparatus for fragmenting automobile tires and analogousarticles of rubber or synthetic plastic material which have been frozento make them brittle, so as to separate their material from embeddedreinforcements of textile or analogous substances, a combinationcomprising an impact mill with a rotor mounted for rotation about ahorizontal axis and having a plurality of circumferentially spacedsmooth-surfaced striking elements which move about said axis in anorbital path having an apex to which said striking elements moveupwardly from below at one side of said axis, and from which they movedownwardly at the other side of said axis; feeding means for gravityfeeding articles to be fragmented in a downward direction, to be hit bysaid striking elements at said one side and in the region of said apex;a housing surrounding said rotor and forming a chamber extending fromsaid feeding means in direction of rotation of said rotor, said chamberhaving an outlet for material fragments; smooth-surfaced impact elementsarranged in said chamber above said rotor and at said other side and sospaced from said rotor that articles hit by said striking elements arefreely flung against the impact elements and can feely drop back uponsaid rotor to be hit again; a screen for screening said fragments whichissue from said outlet; and a hammermill which receives the screenedfragments and particularizes them.